Certificate of correction



United States Patent NEW PYRAZ'OLO-PYRIMIDINES Jean Druey, Riehen, and Paul Schmidt, Therwil, Basel Land, Switzerland, assignors to 'Ciba Pharmaceutical Products Inc., Summit, NJ.

No Drawing. Filed June 20, 1957,- Ser. No."667,042 Claims priority, application Switzerland 'July 16, 1956" 9 Claims. (Cl. 260-256(4) This invention relates to new pyrazolo-pyrimidincs and a process for making same. More particularly, the invention concerns l-iso-propyl-pyrazolo(3,4-d)pyrimidines of the formula I I6 2N in which R represents a free or substituted amino or mercapto group, a substituted hydroxyl group or a halogen atom, and R has the same meaning or represents hydrogen, and salts thereof.

The substituted amino groups are monoor di-substituted especially by one or two lower hydrocarbon radicals, whereby the hydrocarbon radicals may be interrupted also by hetero atoms, such as oxygen, nitrogen or sulfur.

Lower monoor dialkylamino groups, such as methylamino, dimethylamino, ethylamino or diethylamino groups and the furfurylamino group may be especially mentioned.

A substituted mercapto or hydroxyl group is more especially a lower alkylmercapto or lower allgoxy group,

t I N. N N

5 CH: CH;

and salts thereof.

The new compounds are obtained when 2-isopropyl-3- amino-pyrazole-4-carboxylic acid and a carboxylic acid having only 1 carbon atom are reacted together in the form of their functional derivatives or the free acids, care being taken that at least one of the .two carboxyl groups in the reaction participants contains an unsubstituted amino group, and in the resultingpyrazo1o-pyrimidines free nuclear hydroxyl groups are substituted or 2,980,677 I Patented Apr. 18, 1961 replaced directly or stepwise by free or substituted amino or mercapto groups or halogen atoms.

For the reaction with the aminopyrazoles there are used primarily functional derivatives of formic acid or carbonic acid, such as for example formamide, urea, thiourea, gua'n-idine, or if the functionally converted carboxyl group of the pyrazole compound contains an unsubstituted amino group, such as for example in the amide, thioamide or amidine grouping, a halogen formic acid ester or a carbonic acid dihalide, for example, chloroformic acid ester or phosgene. Functional derivatives of the amino-pyrazole-4-carboxylic acid are, for example, esters, amides, thioamides, amidines or the nitrile.

The'condensation of the aminopyrazoles to the pyrazolo-pyrimidines takes place advantageously at temperatures above C., if desired in the presence of diluents and/ or condensing agents in an open or closed vessel.

The conversion of nuclear hydroxyl groups takes place in the customary manner, preferably by halogenation, for example with halides of phosphoric acid, such as phosphorus oxychloride or phosphorus pentachloride, or the corresponding bromides, and, if desired, by subsequently exchanging the halogen atoms for free or substituted amino or mercapto groups or substituted hydroxyl groups, advantageously by treatment with ammonia or hydrogen sulphide or the corresponding amines, mercaptans or alcohols, the hydrogen sulfide or the alcohols or merc'a-ptans being used with advantage in the form of their metal compounds or in presence of condensing agents. Instead of hydrogen sulfide, thiourea or other agents yielding hydrogen sulfide may be used with advantage. Free nuclear hydroxyl groups can also be replaced directly by mercapto groups, e.-g. by treatment with sulfurizing agents, such as phosphorus pent-asulfide.

Depending on the nature of the substituents present in the products they may be converted into various kinds of salts. When they contain free mercapto groups they can be converted into metal salts, eg by dissolving in a solution of alkali. Compounds of basic character, such as those containing basic substituents form therapeutically useful acid addition salts with inorganic or organic acids such as hydrohalic acids, sulfuric acid, phosphoric acid, nitric acid, perchloric acid; aliphatic, a licyclic, aromatic or heterocyclic carboxylic acids or sulfonic acids, such as formic acid, acetic acid, propionic acid, oxalic acid, succinic acid, glycollic acid, lactic acid, malic acid, tartaric acid, citric acid, ascorbic acid, hydroxymaleic acid, dihydroxymaleic acid or pyruvic acid; phenylacetic acid, benzoic acid, p-aminobenzoic acid, anthranilic acid, p-hydroxybenzoic acid, salicylic acid or p-aminosalicy-lic acid; methane-sulfonic acid, ethane-sulfonic acid, hydroxyethane-sul-fonic acid, ethylene-sulfonic acid; toluene sulfonic acid, naphthalene sulfonic acid or sulfanilic acid.

In the above process it is of advantage to use starting materials which lead to the pyrazolopyrimidines indicated above as being especially valuable.

The 2-isopropyl-3-aminopyrazoles, which are unsubstituted in S-pcsition and contain in 4-position a free or functionally converted carboxyl group, used as starting materials are obtained, for example, by reacting u-cyano fl-formyl-acetic acid or functional derivatives thereof, such as esters, amidines, amides or the nitrile and/or enol ethers, acetals or mercaptals with isopropyl hydrazine. As functional derivatives of u-cyano-B-formyhacetio acid there are used preferably enol ethers of a-cyano-fl-formylacetic acid esters, such as for example, the ethoxymethyl ene cyanoacetic acid ethyl ester. The condensation to form the pyrazoles takes place under mild conditions, partly at room temperature; it is an exothermic reaction. It is also possible'to carry out the operation at a raised temperature and in the presence of a condensing agent, such as for example, in the presence of an acid. The

presence of a diluent, such as an alcohol, toluene .or chloroform, is of advantage. In the resulting 3-aminopyrazoles the free or functionally converted carboxyl group can be further converted in the usual manner.

The aforementioned pyrazolopyrimidines, their salts or mixtures thereof can be used, for example, in the form of pharmaceutical preparations. These preparations contain the said compounds in admixture with a pharma-. ceutical organic or inorganic carrier material suitable for enteral, parenteral or local application- For the production of these preparations such substances are con-. cerned' as do not react with the new compounds, as for example water, gelatine, lactose, white petroleum jelly, starch, magnesium stearate, talc, vegetable oils, benzyl alcohols, gums, polyalkylene glycols, cholesterol or other known medicament carriers. The pharmaceutical preparations can take the form, for example, of tablets, dragees, or are in liquid form as solutions, suspensions or emulsions. They may be sterilized and/or contain auxiliary substances, such as preservatives, stabilizing, wetting or emulsifying agents. They may also contain other therapeutically valuable substances. The pharmaceutical preparations are formulated by the usual methods.

The following examples illustrate the invention:

Example 1 19.7 grams of 2-isopropyl-4-carbethoxy-3-aminopyrazole are heated for 4 hours in a bath having a temperature of ZOO-210 C. with 50 grams of formamide. After cooling, the reaction mixture is taken up in 2 N-caustic soda solution, treated with animal charcoal, and the product precipitated by adjusting the pH to 3 with 2 N-hydrochioric acid. There is obtained 1-isopropyl-4-hydroxypyrazolo(3,4-d)pyramidine of the formula i lrl A an. Cs CH3 in the form of white crystals of melting point 53 C.

The 2-isopropyl-4-carbethoxy-3-amino-pyrazole used as starting material can be prepared as follows:

8.2 grams of isopropylhydrazine are introduced into .a solution of 16.9 grams of ethoxymcthylene' cyanoacetic acid in 100 cc. of alcohol and heated at the boiling temperature for 12 hours. The mixture is then evaporated to dryness under reduced pressure and the residue distilled in vacuo. 2-isopropyl-3-amino-4-carbethoxypyrazole of the formula 021150 0 CW HzN- N passes over at l64-l66 C. under a pressure of ll) mm. and solidifies in crystalline form in the receiver. The colorless crystals obtained melt between 46 and 48 C.

Example 2 9 grams of 1-isopropyl-4-chloro-pyrazolo(3,4-d)pyrimi dine and 50 cc. of liquid ammonia are heated at C. for 5 hours in a sealed tube. After evaporation of the liquid ammonia there remains a white product which is extracted with methylene chloride. After evaporation of the latter the residue is recrystallized from cyclohexane. The resulting 1-isopropyl-4-amino-pyrazolo(3,4-d)pyrimidine of the formula iTlHi N t l N CH forms white crystals of melting point 152153 C.

Example 3 i A solution of 10 grams of 1-isopropyl-4-chloro-pyrazolo(3,4-d)'pyrimidine in 250 cc. of toluene is mixed with 10 grams of furfurylamine and then heated to the boiling temperature for 10 hours. The mixture is then evaporated to dryness, the residue mixed with 100 cc. of 1 N-caustic soda solution, .and'the alkaline suspension extracted with chloroform. The chloroformic extract is recrystallized from much petroleum ether. There is obtained in this manner 1-isopropyl-4-furfurylamino-pyrazolo 3 ,4-d pyri- NHCH l 2- o lTl.

midine of the formula \NA /CH CH3 orra in the form of white crystals of melting point -141 C. By direct recrystallization of the chloroformic residue from alcoholic hydrochloric acid the hydrochloride of the above compound is obtained in the form of white crystals of melting point 183-184 C.

Example 4 isopropyl 4 methylamino-pyrazolo(3,4-d) pyrimidine of the formula ITIH O H:

U .\NN/

in the form of white crystals of melting point 65-66 C.

Example 6 grams of 2-isopropyl-3-amino-4-carbamy1-pyrazole and 20 grams of urea are mixed well and heated for one hour in a bath at 200 C. The hot melt is then poured into 150 cc. of l N-caustic soda solution, treated with animal charcoal and suction-filtered. The pH of the filtrate is adjusted to 3 with hydrochloric acid, whereupon white crystals separate. By recrystallizing the precipitate from Water there is obtained 1-isopropyl-4:6- dihydroxy-pyrazolo(3,4-d)-pyrimidine of the formula N l H k N O \N ITT/ CH Cz CHs in the form of white crystals melting at 286-287 C.

' (with decomposition).

10 grams of 1-isopropyl-4:6-dihydroxy-pyrazolo(3,4-d) pyrimidine and 140 cc. of phosphorus oxychloride are heated together in a sealed tube for hours at 160 C. A little undissolved matter is removed by filtration with suction. The phosphorus oxychloride is evaporatedunder reduced pressure, the residue is extracted with chloroform, the chloroformic solution is washed with water and the chloroformic residue crystallized from a very little petroleum ether. There is obtained l-isopropyl-4:6- dichloro-pyrazolo(3,4-d)pyrimidine of the formula CH C CHa in the form of yellowish crystals melting at 67 68 C.

The starting material is prepared as follows: 30 grams of isopropyl-hydrazine are added to a solution of 48.8 grams of ethoxymethylene-malonitrile in,

500 cc. of alcohol. The whole is then heated for 10 hours at the boil, evaporated to dryness under reduced pressure and crystallized from much isopropyl ether. There is obtained 2-isopropy1-3amin0-4-cyanopyraz0le in the form of white crystals melting at 94-95 C. 10 grams of this compound are mixed with 200 cc. of 2 N- caustic soda solution and cc. of alcohol, and the solution heated for 3 hours at the boil. The alcohol is evapo rated under reduced pressure, the residue is allowed to cool and the precipitate filtered. The latter isrecrystallized from alcohol. There is obtained 2-isopropyl-3- amino-4-carbamyl-pyrazole of the formula HzNOC N HzN N a CH3 CH3 in the form of white crystals melting at 2l5-216 C.

Example 7 7.7 grams of 1-isopropyl-4:6-dichloro-pyrazolo(3,4-d) pyrimidine are added to a solution prepared from 2.3 grams of sodium and 200 cc. of methanol. The whole is boiled for 6 hours. After cooling, the precipitated sodium chloride is filtered OE, and the filtrate is. evaporated to dryness under reduced. pressure. The residue is recrystallized from petroleum ether and there is obtained 1 isopropyl-4:6-dimethoxy-pyrazolo(3,4-d) pyrimidine of the formula CH3 CE:

in the form of white crystals melting at 74-75 C.

Example 8 10 grams of 1-isopropyl-4:6-dichloro-pyrazolo-(3,4-d) pyrimidine and 70 cc. of liquid ammonia are heated in a sealed tube for 6 hours at 100 C. After evaporation of the liquid ammonia there remains a solid product which is extracted with cc. of water to separate oif the ammonium chloride. The product which is sparingly soluble in water can be recrystallized from methylene chloride. There is obtained 1-isopropyl-4 amino-6-chloropyrazole (3,4-d)pyrimidine of the formula QLL l N r N N fir CH3 CH3 in the form of white crystals melting at 260-261 C.

Example 9 10 grams of 1-is0propyl-4:6-dichloro-pyrazolo-(3,4-d) pyrimidine and 70 cc. of liquid dimethylamine are heated for 5 hours at 100 C. in a sealed tube. After evaporation of the liquid dimethylamine a product remains which is recrystallized from petroleum ether. There is ob- 7 tained 1-isopropyl-4 6-bis-dimethylamino-pyrazolo-(3;4- d)pyrimidine of the formula wnmm I OH

CH3 CE; in the form of white crystals melting at 135-136" C. The compound forms a hydrochloride melting at 206- 207 C.

Example 10 A solution of 9 grams of l-isopropyl-4-chloropyrazolo (3,4-d)pyrimidine and 8.5 grams of thiourea in 150 cc. of alcohol is heated for 12 hours at the boil. The mixture is evaporated to 70 cc. under reduced pressure and then allowed to cool. 1-isopropyl-4-mercapto-pyrazolo- (3,4-d)pyrimidine of the formula soon precipitates in the form of yellow crystals melting at 207208 C.

Example 11 15.5 grams of l-isopropyl-4-chloro-pyrazolo-(3,4-d)- pyrimidine and 50 cc. of liquid dimethylamine are heated for 5 hours at 100 C. in a sealed tube. After evaporation of the dimethylamine, the residue is dissolved in wa ter, the pH is adjusted to 9 with 1 N-caustic soda solution and the residue extracted with chloroform. After evaporation of the chloroform there crystallizes l-isopropyl-4-dimethyl-amino-pyrazolo(3,4-d)pyrimidine of the formula CH Cs CHa in the form of white crystals melting at 6970 C. The hydrochloride melts at 239-241 C.

Example 12 18 grams of 1-isopropyl-4-ch1oro-pyrazolo(3,4-d)- pyrimidine and 50 cc. of liquid diethylamine are heated for 5 hours at 90l00 C. in a sealed tube. After evaporation of the diethylamine, the residue is taken up in wa ter and the aqueous solution extracted with ether. The ethereal residue is a colorless oil. It is taken up in a alcoholic hydrochloric acid. On evaporating the solution, the hydrochloride of 1-isopropyl-4-diethylaminopyrazolo( 3,4-d) pyrimidine of the formula C 3 CH3 crystallizes in the form of white crystals'melting at 165- 167 C.

Example 13 OHsHN LN 3H(OHa)i in the form of white crystals melting at 227-229" C.

Example 14 10 grams of 1-isopropyl-4:6-dichloro-pyrazolo(3,4-d)- pyrimidine and 70 cc. of B-diethylamino-ethylamine are boiled under reflux for 3 hours. The excess p-diethylaminoethylamine is distilled oil in vacuo, the residue is taken up in cc. of water, the pH adjusted to 9 with 2 N-caustic soda solution and the residue extracted with chloroform. The chloroformic residue is distilled at 210- 225 C. under 0.2 mm. of pressure. There is obtained 1-isopropyly-4:G-biSQQ-diethyl-amino ethylamino)-pyrazolo(3,4-d)pyn'midine of the formula HUJHa):

in the form of a viscous oil.

What is claimed is:

1. 1*isopropyl-4-methoxy-pyrazolo(3,4-d)pyrimidine.

2. A therapeutically useful acid addition salt of a compound claimed in claim 1.

3. l-isopropyl 4,6 dimethoxy-pyrazolo(3,4-d)pyrimidine.

4. A therapeutically useful acid addition salt of a com pound claimed in claim 3.

5. l-isopropyl-pyrazolo(3,4-d)pyrimidines of the formula wherein R represents a lower alkoxy group and R represents hydrogen.

6. l-isopropyl-pyrazolo(3,4-d)pyrirnidines of the formula CHa wherein R represents a lower alkoxy group and R represents halogen.

. 10 7. l-isopropyl-pyrazolo(3,4-d) pyrimidines of the for- References Cited in the file of this patent 3 UNITED STATES PATENTS R, 2,691,043 Husted et al Oct. 5, 1954 5 2,802,005 Heidelberger Aug. 6, 1957 FOREIGN PATENTS Great Britain Oct. 6, 1954 OTHER REFERENCES Rose: Iour. Chem. Soc. (London), pp. 3448-3454 (1952). 7

Abstracts of American Chemical Society, 128th meeting, pp. 11Nl3N (1955).

Falco et al.: Journ. Amer. Chem. Soc., vol. 78, pages 15 3143-3145 (1956).

Robins: Iour. Amer. Chem. Soc., vol. 78, pages 784- H 10 Ca \CH3 wherein R represents a lower alkoxy group and R represents a lower alkoxy group.

8. A therapeutically useful acid addition salt of a compound claimed in claim 5. 788 (1956).

9. A therapeutically useful acid addition salt of a com- Schmidt et al.: Helvetica Chimica Acta, vol. 39, pp. pound claimed in claim 7. 986-989 (1956).

pyrazo1o(3,4-d)pyrimidine column 5, line 15, for "-isopropypropyl-" read -is0propylcolumn 8, l1ne 31, for "-isopropylye' lzbisw read isopropyl4: 6-b1s-({3 I UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 2,980,677- I April 18, 1961 Jean Druey et a1.

It is hereby certified that error appears in the above numbered petent requiring correction and that the said Letters Patent should read are corrected below.

Column 8, line 35, for "pyrazolo(3,4d)pyramidine"' read Signed and sealed this 5th day of December 1961.

(SEAL) Attest:

ERNEST W. SWIDER DAVID L. LADD Attesting Officer Commissioner of Patents USCOMM-DC 

5. L-ISOPROPYL-PRYAZOLO(3,4-D)PYRIMIDINES OF THE FORMULA
 7. L-ISOPROPYL-PYRAZOLO(3,4-D)PYRIMIDINES OF THE FORMULA 